Sensory conflicts are very common in everyday life. If sensory conflicts are not eliminated or greatly reduced, they might cause problems to human health, such as motion sickness. Sensory perception plasticity is believed to ameliorate motion sickness by reducing sensory conflict. When presented with spatially conflicting visual and vestibular cues, both vestibular and visual perceptual psychometric functions shift in the direction required to reduce cue conflict. However, currently little is known about the neural correlates of vestibular plasticity perception. No related neuron or process has yet been physiologically identified. The proposed experiments aim to eliminate this knowledge gap. The goal of this research is to uncover the neural basis of vestibular sensory perception plasticity mechanisms. The research will focus on the parieto-insular vestibular cortex (PIVC). There are two specific aims. In Aim 1, PIVC neurons will be recorded before and after the presentation of conflicting visual and vestibular motion stimuli. If PIVC neurons are involved in neural process of vestibular perception plasticity induced by the conflicting visual cues, it is expected that PIVC neural tuning curves will shift in the direction required to reduce the spatial conflict between visual and vestibular cues, consistent with the shift of vestibular psychometric function. Whether and how population performance changes following the shift of neural response tuning curves will be studied with decoding simulations from neural responses, based on the measured tuning curve shift and response statistics of PIVC neurons. In Aim 2, the causal role of area PIVC in vestibular perception plasticity will be examined by manipulating neural activity using reversible chemical inactivation and then observing its impact on vestibular perception plasticity. If the vestibular psychometric function shifts are either completely eliminated or greatly reduced after reversible chemical inactivation of area PIVC, it will suggest neural activity in PIVC is causally linked to vestibular plasticity. This research is important for understanding vestibular perception plasticity and establishing novel directions for both basic and clinical research studies.